Medical Imaging and Clinical Research

Invasive respiratory support is a cornerstone of Critical Care Medicine, however, protocols for withdrawal of mechanical ventilation are still far from perfect. Failure to extubation occurs in up to 20% of patients, despite a successful spontaneous breathing trial (SBT).We prospectively included ventilated patients admitted to medical and surgical intensive care unit in a university hospital in northern Mexico. At the end of a successful SBT, we measured Diaphragmatic Shortening Fraction (DSF) at the end of inspiration and at the end of expiration, and the presence of B-lines in five zones of the right and left lung. The primary objective was to determine whether analysis of DSF and Pulmonary Ultrasound improves prediction of extubation success. Eighty-two patients were included,24 (29.2%) failed to extubation. At univariate analysis, DSF (Youden’s J: > 30% [sensibility and specificity 62 and 50%, respectively])and number of B-lines zones (Youden’s J: > 1 zone [sensibility and specificity 66 and 92%, respectively]) were significant related to extubation failure (area under the curve 0.664 [0.526 to 0.801] and 0.819 [0.703 to 0.934], respectively). At the binomial logistic regression, only the number of B-lines zones remains significantly related to extubation failure (OR 5.91 [2.33-14.98], p < 0.001). In patients with a successfully SBT, the absence of B-lines significantly decreases the probability of extubation failure. DSF analysis does not add predictive power over the use of pulmonary ultrasound.